1. Field of the Invention
This invention relates to a novel coil spring mounting cone apparatus and method and more particularly, to novel improvements in the anchor cone and winding cone attached to each end of a coil torsion spring.
2. The Prior Art
The overhead door is a well known fixture in many homes and businesses where it is used as a closure for large openings such as garage openings, loading docks, and the like. The overhead door derives its name from its function of being raised from its vertical, closure position to a horizontal or overhead, open position. Overhead doors used as closures for large openings are very heavy so that some form of counterbalance or spring system is commonly employed to compensate for at least a portion of the weight of the overhead door both during opening as well as closing of the overhead door.
The coil torsion spring has been adapted throughout the industry as one very efficient mechanism for providing the necessary forces to offset the weight of the overhead door. Customarily, the coil torsion spring is formed into a righthand and a lefthand section mounted over a torsion bar. The respective ends of the spring sections are anchored end-to-end by anchor cones secured to a wall-mounted bracket. The coil torsion spring is formed into two sections with the right and left hand winding to compensate for the axial forces exerted by each spring section as it coils and uncoils. The end-to-end mounting of the spring sections means that the axial force of each spring section is directed against the central mounting bracket.
The free ends of each section of spring are mounted to winding cones that are, in turn, adjustably secured to the torsion bar. The winding cones allow the operator to adjust the tension transmitted to the torsion bar by the individual sections of coil torsion spring. Set screws in the winding cones are used to releasably secure the winding cone to the torsion bar. Cable drums at each end of the torsion bar reel and unreel cable extending to the bottom edge of the overhead door so as to transmit the support forces provided by the coil torsion spring directly to the overhead door.
Each section of coil torsion spring is assembled at the factory with the appropriate winding cone and anchor cone mounted in the respective end. The external diameter of each cone at the terminal end is incrementally smaller than the internal diameter of the spring while the external diameter of the basal end is incrementally larger than the internal diameter of the spring so as to cause the spring to tightly grip the particular cone. Accordingly, during assembly the manufacturer "screws" a cone into the end of the spring and relies on the gripping action of the spring to securely hold the cone in place. Once mounted on the torsion bar, each spring contributes its torsional forces in the same rotational direction on the torsion bar.
The coil torsion springs are each designated as either right wound or left wound. It has been customary in the trade to place the left wound spring with its winding cone on the right side of the coil torsion spring assembly (when viewed from inside the garage). The left winding cone is painted black as an indicator for its location on the right side. Correspondingly, it is also customary to place the right wound spring with its right winding cone on the left side of the coil torsion spring assembly. The right winding cone is painted red to indicate its placement on the left side of the coil torsion spring assembly. Confusion frequently occurs in determining the correct placement for the black and red winding cones. However, even more confusion exists as to which direction the black-painted and red-painted winding cones should be rotated to impart the desired increase in tension on the coil torsion spring assembly.
The foregoing confusion as to direction of rotation is particularly relevant since an inexperienced operator will, upon casual observation of a coil torsion spring and the manner in which it is secured to the winding cone, conclude that to increase tension on a coil torsion spring it is necessary to attempt to "screw" the winding cone more tightly to the spring whereas the opposite is the correct direction of rotation. In other words, it is necessary for the operator to appear to be attempting to "unscrew" the winding cone in order to increase tension on the spring.
Further, it is estimated that an overhead door is subject to hundreds of cycles during each year of installation over the opening to the garage in a dwelling. I have discovered that the conventional anchor cone and winding cone each terminate in a surface that is perpendicular to the axis of the cone. This surface presents an extended surface over which the corresponding coil of spring rubs or chafes during each cycle of the overhead door with a substantial increased incidence of breakage at that point.
It would, therefore, be an advancement in the art to provide improvements in anchor cones and winding cones as well as methods for mounting the coil torsion spring to the anchor cones and winding cones. It would also be an advancement in the art to provide anchor cones and winding cones with indicia to clearly indicate which side the coil torsion spring assembly the particular section of coil torsion spring is to be mounted. Another improvement would be a winding cone with arrows indicating the direction the winding cone is to be rotated to increase tension on the coil torsion spring. Another advancement would be to provide an abrupt termination of the spiral groove on the frustoconical face of the anchor cone and the winding cone to reduce chafing and wear on the corresponding spring coil during cycling of the coil torsion spring. Such a novel apparatus and method is disclosed and claimed herein.